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MAY, 1920 




CORNELL UNIVERSITY 
AGRICULTURAL EXPERIMENT STATION 



THE RIBBED PINE-BORER 



WALTER N. HESS 



ITHACA, NEW YORK 
PUBLISHED BY THE UNIVERSITY 



1^1 ^^c4XE-tr>t4v\ 



MAY. 1920 MEMOIR 33 

CORNELL UNIVERSITY 
AGRICULTURAL EXPERIMENT STATION 



THE RIBBED PINE-BORER 




WALTER N. HESS 



ITHACA, NEW YORK 
PUBLISHED BY THE UNIVERSITY 



% 



10 



THE RIBBED PINE-BORER 



THE RIBBED PINE-BORERS 

Rhagium Uneatum Oliv. 

Walter N. Hess 
Order, Coleoptera Family, Ceramhijcidae 

The ribbed pine-borer {Rhagium lineatiim Oliv.) is one of the commonest 
and most widely distributed species of cerambycids in North America. 
It is especially abundant in the vicinity of central Peimsylvania and about 
Ithaca, New York, where this study was conducted. Since these insects 
are very abundant and the limited literature concerning them contains 
Httle information regarding their life history, it has seemed advisable to 
make a more careful study of their habits. 

A number of authors have .briefly discussed the economic importance of 
the insect. Their reports, however, are conflicting and indefinite". 

HISTORY OF THE SPECIES 

The ribbed pine-borer, originally described b.y Olivier \n 1795, has 
subsequently bcHMi l^riefly referred to by many authors. Kirby (1837) 
reports the insect from latitude 54°, and also from JXIassachusetts. Harris 
(1842) found the larvae of the species living bc^tween the bark and the 
wood of pitch pine. He states that they attack living tr(>es, often exten- 
sivel}^ loosening th(i bark, which falls off in large flakt^s as a result and the 
trees die. LeConte (1850) states that the insects are found from Maine 
to Chihuahua, Mexico. 

Rathvon (1862) describes the larva as a whitish grub about ai,i inch 
long. He found larvae in large numbers just underneath the bark of 
trees, which they caused to fall off in large pieces, frequently resulting 
in the death of the trees. Packard (1883) reports the larvae as very 
common under the bark of pines that have becni cut down for a year 
or more. He foimd the chief injury to consist in the loosening of the 
bark, which forwards the decay of dead timber. Hopkins (1899) found 
the insects to be very common bark borers, mining under the bark 



' The author is iiKlchtcd to Profossor Glenn W. Herritk and Dr. Robo't Matheson, of the Department 
of Entomology at Cornell University, under whose direction this study was made. 

367 



368 Walter N. Hess 

of dying and dead pine trees. He records the presence of larvae on 
July 14; pupae in October, and adults on April 8, May 5 and 9, October 17, 
and December 19. 

Felt (1906) thinks these insects should not be considered injurious to 
Uving trees, as they live in rotten wood. Their operations, together with 
those of associated insects, soon loosen the bark so that it falls off in large 
sheets. Felt found the grubs transforming to adults during the latter 
part of the summer, in specially constructed pupal cells miderneath the 
bark. 

SYNONYIVIY 

The ribbed pine-borer belongs to the order Coleoptera, family Cerambyc- 
idae, subfamily Cerambycinae, genus -Rhagiimi, species lineatum. Tliis 
species was first described by Ohvier (1795) as Stenocorus lineatus, but was 
later placed in the genus Rhagium. Several workers, chiefly European, 
consider tliis insect the American form of thp European species inquisitor, 
and hence give it varietal rank under tliis species as Rhagium inquisitor 
lineatum Ohv. There seems to be good reason for considering this species 
the same as the European inquisitor; however, since American workers 
list the American form as a distinct species, it is so considered in this 
discussion. 

DISTRIBUTION 

The rib])cd pine-borer is commonly and widely distributed throughout 
the greater part of North America. It has been reported from twelve 
States in this country, in addition to Chihuahua (Mexico), Vancouver, 
and the Mackenzie River region of Canada. The States from which it 
has been reported are Maine, IMassachusetts, New York, Pennsylvania, 
Virginia, North Carohna, Maryland, Louisiana, Michigan, New Mexico, 
Idaho, and Oregon. From these do.ta it seems probable that the beetle 
ranges in distribution from northern jNIexico to central Canada, extending 
across the continent from coast to coast wherever pine is found. 

The species inquisitor, with which this species is often grouped, is widely 
distributed in the Old Wotld. It has been reported from Europe, Siberia, 
Syria, and Japan. 

HOSTS 

All of the common species of pine in New York and Pennsylvania are 
attacked by the ribbed pine-borer. The species most commonly found 



The Ribbed Pine-Borer 3G9 

infested are the white pine (Pinus strobus L.), the pitch pine (Pinus 
rigida MilL), and the red pine {Pinus resinosa Ait.). 

Tliese insects are usually reported as pine insects, and it seems probable 
that they attack all or nearly all species of pines throughout t\Ce United 
States and southern Canada. The writer has never found them infesting 
other conifers, such as larch and spruce, though it is possible that they 
may attack these at times. 

METHODS OF BREEDING 

Numerous attempts were made by the writer to detei-mine the molts 
of this insect, but with httle success. For this purpose pieces of bark 
were taken to the college insectary, cavities were made on the inner side 
of the bark, and larvae were placed in these cavities and covered with strips 
of celluloid as shown on Plate VIII, 5 and 6. The bark was kept in dark, 
moist jars, where, it was easily accessible for examination. Though these 
larvae lived for many months in an apparently normal condition, they never 
reached maturity. For maldng shorter observations, such as that of 
the pupal stage, this process was very satisfactory, 

LIFE HISTORY AND DESCRIPTIONS 

The adult 

This species, Rhagium lineatum Oliv., no doubt owes its specific name 
to the three smooth, rather strongly elevated, Hues or ribs extending 
lengthwise along each elytron. The beetle is elongate, rather robust, 
and black mottled with reddish brown and gray. The greater part of 
its surface is covered with grayish hairs, giving it a grayish pubescent 
appearance. 

The head, which is slightly narrowed beliind the eyes, is attached to 
the thorax by a short neck. The antennae are short, scarcely reaching 
the bases of the elytra ; they are not enveloped by the eyes but are inserted 
in front of and between them. The maxillarj^ palpus is longer than the 
labial palpus; the last segment of each is bluntly pointed. The lab rum is 
free. The eyes are oblong and slightly emarginate. The mandibles are 
flat, acute, and fringed on the inner margin. 

The thorax is cylindrical, not margined, and nnich nari-ower than the 
elytra. It is armed on each side with an acute tubercle. 



PLATE \1II 

1. Rhagium lineatum, male 

2. Rhajium lineatum, female 

3. Larva of Rhagium lineatum 

4. Pupa of Rhagium lineatum 

5. Inner view of pine bark, showing celluloid strip underneath which are various stages 
of Rhagium lineatum larvae 

6. Liner view of pine bark, showing the arrangement of celluloid strips used in rearing 
larvae and pupae 

7. Liner view of pine bark, showing four pupal cells. Photograph taken on April 8. 
The strips of wood woven into the frass in constructing the cells can be distinctly seen. 
Tlio depressions at the sides of the pupal chambers were made by the adults in preparation 
for emergence. The lower cell shows a hole made by a woodpecksr 

8. Inner view of pine bark, showing in the pupal cell a larva of Rhagium lineatum 
which has been killed by a fungus 

9. Pupal cell of an Atanycolus simplex which has parasitized a Rhagium lineatum larva. 
The exit hole of the parasite can be seen at the lower end of the pupal cell. The head of 
the parasitized larva is lying at the upper left side of the pupal cell 

10. Egg mass on pine bark, exposed by removing a strip of the loosa outer bark 



Memoir 33 



Plate VIII 







The Ribbed Pine-Borer 371 

The front coxae arc conical and prominent; their cavities are open and 
are angulated externally. The front tibia has no oblique groove on the 
inner margin. The hind tibial spurs are terminal. The prostcrnum pro- 
jects prominently between the coxae. 

The eljiira are gradually narrowed from about the middle to the apex. 
The intervals between the longitudinal ridges are coarsely and sparsely 
punctate. 

The chief character that usually distinguishes this beetle is the extensive 
projection of the prosternum between the prominent fore coxae. Its 
general pubescence mottled with grayish brown and black, together with 
the short antennae, usuall}^ readily identifies this species. 

The sexes arc of the same general uniform coloration, but usually differ 
in two distinguishing characters: (1) the female (Plate VIII, 2) is 
about 3 milUmeters longer and proportionally larger than the male 
(Plate Vni, 1); and (2) the tip of the abdomen is exposed in the female, 
while in the male it is entirely concealed by the elytra. The insects vary 
in length from 12 to 18 millimeters. Those found in small trees with 
thin bark, and hence scanty food, are usually smaller than those found in 
larger trees. 

During the warm days of early spring the beetles become active in their 
pupal cells, and gradually begin gnawing through the bark to the exterior. 
The time of emergence is usually during the last week in April, but this 
may vary a week or more, depending on weather conditions. The beetles 
are active as soon as they emerge, and fly readily if disturbed. 

Since these insects winter as adults the reproductive organs have had 
sufficient time to mature. In the spring the female's ovaries are full of 
large eggs. Copulation occurs as soon as the adults emerge. It occurs 
frequently, and a pair may remain in copula for several hours. In fact, 
during the first few days after emergence, this process may be repeated 
again and again at different times. One pair was taken in copula as 
late as the last week in June. 

Although this beetle is a pine insect, and although it feeds on the bark 
after Ijecoming an adult, it ceases to feed on pines after emerging. It 
then becomes a pollen feeder, feeding on such flowers as the dogwood — 
a habit which it has in common with many of its near relatives among 
the cerambycids. 



372 



Walter N. Hess 




Fig. 61. egg of rhagium lineatum, 
showing markings 



The egg 
Wlien laid, the egg is pure wliite in color and is somewhat \'igcoiis, with 
a thin, fragile shell. It is ovoid in shape, being widest near the anterior 
end and tapering slightly toward the posterior. The shape, however, 

varies considerably, since owing to 
the softness of the shell it is easily 
modified by the shape of the crevice 
in which the egg is deposited. The 
entire surface is marked with very 
irregular elongate areas (fig. 61). The 
egg measures 1.9 millimeters long by 
0.7 millimeter wide. 
The egg stage lasts from eight to ten days, varying with weather con- 
ditions. In emerging, the young larva ruptures the egg in the lateral 
anterior region, usually on the right side. This it does by rubbing the 
sides of its head against the sides of the chorion, finally 
slitting the latter longitudinally. On each side of the head 
is a group of coarse setae which probably function in this 
process. 

The larva 

The newly hatched larva (fig. G2) is whitish in color and 
is slightly flattened. It is more rounded, however, than the 
mature larva, resembling rather the typical cerambycid 
type. The heatl and the thorax are slightly wider than the 
abdomen. The head is light brown in color, as are also 
the mouth parts except for the mandibles, wliich are dark 
brown toward the tips. At each side of the head is a group 
of coarse setae with dark brown chitinizcd basal parts, while 
scattered over the entire larva are a number of slender, 
elongate setae. 

Very soon after emergence, the newly hatched larva works 
its way through the outer bark into the cambium layer, 
where the larval hfe is spent. The larva at this stage is 
very dehcate and soon perishes unless it reaches the cambimn layer, where 
it begins at once to feed. 

The mature larva (Plate VIII, 3) h long and is very much flattened, 
as a result of which it has been incorrectly called a flat-headed borer 




Fig. 62. first 
in star of 
larva, dor- 
SAL VIEW 



The Ribbed Pine-Borer 



373 




Fig. 63. clypeus .\nd l.vbrum, dors.\l view 



(Kellogg, 1905). The head is very large and is slightly wider than the 
prothoracic segments. It has a triangular incision behind, the apex of 
which is met by a curved line passing back from the outside of the 
antennae and dividing the epicranium into two areas. The clypeus is 
short and wide. The labrum 
is al^out twice as wide as it 
is long, and is moderately 
rounded in front. The an- 
tennae are small and two- 
segmented, the second joint 
being blunt at the tip. The 
mandiljles are large, with 
three cutting teeth. The 
maxillae are comi^oscd of 
only two segments besides 
the three-segmented palpus. The labium is large, vv-ith a prominent hgula 
which is sHghtly rounded at the front edge. The labial palpi are two- 
segmented. 

The prothorax is of about the same width as the other thoracic segments, 
but is more than twice as long. It has a flat, chitinized surface. The 

thoracic legs are slender and are 
composed of four segments. 

The abdominal segments in- 
crease sHghtly in length pos- 
t.eriorly to the eighth, which is 
loiiger but narrower than the pre- 
ceding ones. The ninth segment 
is of about the same length but 
is narrow(>r than the eighth. The 
tenth is scarcelj' visible from 
above, Ixnng only about one- 
fourth as wide as the ninth; it 
is deeply cleft posteriori j^ 
The mature larva measures from 25 to 30 millimeters in length, 
with a maxunum width of G millimeters in the region of the head 
and the prothorax. The width of the first abdominal segment is 5 
millimeters. 




Fig. 64. left mandible, dorsal view 



S74 



Walter N. Hess 



This larva may undoubtedly be recognized by its habitat in the cambium 
of ret'cntly killed pine trees, by its relatively large size when mature, 
and by its broad, flattened head and body. 



The mouth parts of the larva 

Since these larvae closely resemble in appearance the flat-headed borers, 
the prothorax and the head are very wide and flat, resulting in a rather 
broad, short clypeus and labrum (fig. 63). The clypeus (CI) is very wide 

at its basal part but tapers anteriorly to 
jom the labrmii. The labrum is about 
twice as wide as it is long, and bears 
on its dorsal side man}^ long bristles and 
sense pits. 

The mandibles (fig. 64) are broad and 
heavily chitinized, and bear near the 
apices three rather sharp cutting teeth 
which fit them for both cutting and 
chewing. 

The maxillae of the larva (fig. 65) are 
of a much simpler type than those of 
the adult. The cardo (C) is a distinct 
sclerite, triangular in shape. The 
stipes (S) and the lacinia and galea 
(LG) arc not differentiated but are 
represented by one segment; near the 
apex on the inner margin are many 
long bristles, which probably repre- 
sent the region of the future lacinia. 
The jxdpus (P) is three-segmented. 

The labium (fig. 6(3) is large and covers the greater part of the lower 
side of the head. The submentmn (SM) is broad and short. The 
mentum (M), while narrower than the submentum, is broad and flat. 
It bears tlie ligula (L), from which arise the two-segmented labial 
palpi (P). The greater part of the surface of the labium, but more 
especially the anterior edge of the ligula, bears nmncrous long bristles 
and sense pits. 




Fig. Cm. maxilla, ventral view 



c, ' 



irdo; S, stipes rcfjioii; LG, uudifTercn; 
liated lucinia and galea; P, palpus 



The Ribbed Pine-Borek 



375 



The pupa 

Pupation begins in the latter part of August and continues until late 
in October. Because of the varying temperature at that time of the 
year, the pupal period varies considerably. The individuals that pupated 
in August were found to emerge in from sixteen to twenty days, while 
those that pupated later took a month or even more to complete their 
pupal period. Some were found that wintered as pui)ae, but in every 
case observed these died before spring. When the adults emerge they are 
nearly wliite, and they require from two to five days to become fully colored. 

The pupa (Plate VHI, 4) measures from 12 to 18 millimeters in length. 
It is white in color and 
rather convex in shape, 
and is without any 
special distinguishing 
markings. Scattered 

over its surface are many 
small setae, or spines. 



HABITS 

Of all the insects in- 
festing the pine, few are 
commoner than, or as in- 
teresting to observe as, 
this species of ceramby- 
cid. Where the insects 
were studied in New 




Fig. GG. labilm, ventral view 

SM, submenturii; M, inentuni; L, ligala; P, palpus 



York and Pennsjdvania, they have been found during the winter months 
in large numbers, both as larvae and as adults, underneath the bark of 
white, red, and pitch pine. Here the larvae feed on the decaying tissues 
of the cambium layer. 

The adults, which emerge in early spring, can be found during the last 
of ]\Iay and in June on pines that have recently died. These insects 
always prefer the larger trees, and in this region the pitch pine is preferred 
to the other species, due joossibly to the heavier bark which offers the 
insect more food and better protection. Trees less than six inches in 
diameter seldom, if ever, are infested with this insect; in fact, efforts 
have been made, by using cages, to have females oviposit on logs of tliis 



370 Walter N. Hess 

size, with negative results. Where the insects have been found in trees 
of about this size, they frequently die before maturing, due probably to 
scant}' food and to too Uttle protection from cold and diseases. So far 
as is known , they never infest either trees that have been dead for more 
than three years or healthy living trees. They have been found in trees 
that had been injured by fire or other agencies on one side but were alive 
and healthy on the other side. The insects no doubt do material damage 
to such trees in hastening their death, not only by eating into the tissues 
that may be alive but also in opening and exposing the injured side to 
water and fungus attacks. 

The normal time for these insects to oviposit on pine is in the spring 
following the death of the trees. The insects will oviposit on the trees 
again the second year, but only in rare instances will they do so the third 
year, and never the fourth year in so far as could be determined. In 
fact, by the third year the cambimn layer is so nearly decaj'ed that little 
is left for the larvae to feed upon. 

The insects have been found from the very base of the stumps of the 
infested tree to near the top, where the trees were about six inches in diame- 
ter. They seldom are seen above this, and never in the limbs unless these 
happen to be very large. An idea of the number of individuals that may 
be found in an infested tree is given by notes made in regard to a tree cut 
on March 10, 1916. The tree was 16 inches in diameter at the base and 
was infested to a height of about 30 feet. It had been dead for two years, 
and so two broods were present. There were found 195 adults representing 
the first year's brood, and 155 larvae representing the second year's brood. 
These insects were rather uniformly distributed throughout the tree. 
In some cases they were as close together as two or tlu^ee inches, while in 
other cases they were as much as a foot apart. 

In badly infested trees the mines of these insects are more or less con- 
tinuous by the end of the second or the third year, often separating the 
bark from the trees and not infrequently causing it to fall off. It is 
probable, however, that the burrows of other insects aid in this process. 

Differing from most other cerambycid larvae, the larvae of this species 
move about comparatively little, but feed in all directions from a rather 
stationary point until all food within reach is consumed. They then 
move to one side or the other, leaving a large amount of frass behind them. 
Unto the larvae are about three months old they make no special effort 



The Ribbed Pine-Borer 377 

to protect themselves from enemies. Toward fall, however, they construct 
about themselves a wall from debris, somewhat resembling that of the 
pupal cell. In the spring the larvae leave their winter cells for food, 
but during this second summer they usually keep themselves more or less 
protected by such a barrier. This they tear down and rebuild as they 
move about for food. As a result of this moving about, a rather extensive 
area, in the form of a blotch mine, is finally excavated. 

Diu'ing the esCrly part of August of the second year the larvae prepare 
to pupate. This they do by enlarging and strengthening the chambers 
in which they have recently been feeding, forming what are called pupal 
cells (Plate VIII, 7). These cells are oval in shape, are about | by f inch 
in size, and lie just underneath the bark. They are constructed of frass 
which these or other insects have discarded, and are lined with strips 
of wood which the larvae tear from the bottom of the cells and push 
firmly into their walls. The excavation of the wood insures the insects 
plenty of room as well as a better protection against their enemies. 

During late summer and early fall the second-year larvae transform to 
pupae, which in a period of from four to six weeks change to adults. They 
remain in the pupal cells over winter, emerging as adults the following 
spring. 

SEASONAL HISTORY 

Shortly after copulation, the female can be found on the bark of pine 
trees that have recently died. She walks over the bark, constantl}'- 
searching with her ovipositor for crevices between the layers of tlie corky 
outer bark, in which she deposits her eggs in masses of from one to twenty- 
five or more, depending on the suitableness of the cavity (Plate \TII, 10). 
The writer found masses of eggs that hatched at different intervals, 
indicating that the insects maj^ oviposit in the same cavity more than 
once. 

Egg laying continues from about the middle of May imtil tlie last of 
June or the first of July. Since the eggs all mature at about the same 
time, the number laid by a single female can be easily ascertained. This 
number was found to vary from 120 to 165, indicating that the number 
is comparatively constant. 

The eggs hatch into young larvae in from eight to ten days. As soon 
as they are hatched, they work their way through the bark, where they 
feed during their larval life on the tissues of the cambium layer. 



378 Walter N. Hess 

Since this insect requires two years to complete its life cycle, the first 
winter is spent in the larval stage. From the time of hatching until 
late summer, the larva feeds freely in the cambium, but toward fall it 
constructs about itself a defensive wall of frass. In this condition it 
spends the winter. During the second summer the larvae usually keep 
themselves protected by such a defense, moving about only as they need 
a fresh supply of food. Unlike most larvae, they do not feed in definite 
channels, but move about irregularly, excavating a blotch-like mine 
which is often rather extensive. 

Toward fall (about September) of the second year the larvae transform 
to pupae: About three weeks later they transform to adults. In this 
condition the insects pass the second winter. Toward spring the adults 
gradually gnaw their way through the bark, and emerge about the first of 
May. Though they feed very little before emerging, they eat a part of 
the bark as they bore their way to the exterior. They now no longer feed 
on the pine, but become pollen feeders like many other cerambycids. 
After emerging they soon copulate, and about the middle of May begin 
oviposition. 

• ECONOMIC IMPORTANCE 

Rhagium lineatum, in the strict sense, can hardly be considered as an 
insect of economic importance in so far as any damage to living pines is 
concerned. Though its attack is limited to the region of the inner bark 
and the outer sap wood, it no doubt causes considerable damage to 
recently dead timber. Its excavations are usually extensive, and as a 
result the bark is frequently loosened, allowing moisture to enter. When 
water has once gained access, it is held by the large masses of frass. This 
is favorable for fvmgous growth, and hence the decay of the tree is 
hastened. 

During the second and third years after the trees die, the exit holes made 
by the emerging adults admit large quantities of water, other insects, 
and fungi, by means of which the log is soon rendered useless for commercial 
purposes. 

Natural control 

In the control of the ribbed pine-borer, as in that of many other injurious 
species, nature has provided enemies which, under favorable conditions, 
are very effective in reducing their numbers. A wet season not only 



The Ribbed Pine-Borer 370 

makes it difficult for this insect to work, but (l(>velops fungi which attack 
all stages of the insect, especially the larvae; (Plate VIII, 8). Tliis is 
especially true in the case of trees with thin bark, for such trees are less 
resistant to moisture and the insects may become wet. Under such con- 
ditions the larvae, the pupae, and even the adults often die fi-om fungus 
attacks. Those that survive until winter are often killc^d bj^ frosts, which 
under such conditions are destructive to them. 

The newly hatched larvae, while searching for an easy access to the inner 
bark, often expose themselves to predatory enemies which help in reducing 
their numbers. Birds, chiefly the woodpeckers, are probabty the most 
impoi-tant of these predatory enenli(^s (Plate VIII, 7). It is not unconnnon 
to find infested trees where these lairds have removed from one-half to 
two-thirds of the larvae and adults during a single winter. Ants are 
usually conniion on the trees where the adult beetles are ovipositing. 
Though the insect tries to place her eggs in a secluded crevice, the newly 
emerged larvae often expo-'e t'lemselves. Ants havc^ been observed carry- 
ing off both eggs and 3'oung larvae, chiefly tlu> latter, as food. 

Numerous centipedes, and larvae of stai)hylinids and caral>ids, arc 
frequently found mider the bark with the larvae of this insect, and may 
feed on them. 

Though the insect constructs about itself a defensive wall, it seems 
probable that this wall is often ineffective against these enemies, especially 
in trees on which the bark has become loosened. Large carpentcn- ants 
have been found in the pupal cells of the ri])bed pine-borer, but whether 
or not they are definitely harmful is not known. 

A larval parasite, Atanycohis simplex Cresson,'- which was reared from 
certain larvae, seemed fairly effective in reducing the numbers of this 
insect, especially farther south in Pennsylvania. In no case, howcvei-, 
were more than about five per cent of the larvae found infest(^d. In New 
York this parasite is exceptionally rare, infesting only about one per cent 
of the larvae. When this parasite is mature it emerges from the larva 
and constructs a pupal cell underneath the bark (Plate \TII, 9). This 
occurs during the early fall. The adult emerges the following June. The 
remnants of the old Rhagium larva can often be seen attached to the pupal 
case of this parasite. 



2 Identified by S. A. Rohwer, of the Bureau of Entomology, Washington, D. C. 



380 Walter N. Hess 

Artificial control 

The insect can be artifically controlled by cutting all recently killed 
pines and removing the bark before the first of March. This will kill 
the larvae and the adults, and will do much to lessen attacks the following 
season. Where possible, the placing of newly felled logs in water will 
prevent attack. Putting logs in wet places will greatly reduce infestation, 
though it may hasten the decay of the tunber. Repellents such as carbo- 
lineum, apphed in May, will usually prevent oviposition. 

A few years ago the ribbed pine-borer w^as exceptionally abundant 
about Ithaca; but during the past few years, due to the improved methods 
emjDloj'^ed in this region by the Department of Forestry, at Cornell Uni- 
versity, these insects, together wdth many of the more injurious forest 
insects, have nearly disappeared. This has been largely due to the practice 
of cutting and removing all trees as soon as they die or are found to be 
dying. 



/-■ 



,PC -2 3 



The Ribbed Pine-Borer 381 



BIBLIOGRAPHY 

Felt, E. P. Ribbed pine-borer. In Insects affecting park and woodland 
trees. New York State Mus. Mem. 8-:36G-368. 190G. 

Fitch, Asa. Ribbed rhagiiim, Rhagium lineatiun, Olivier. In Fourth 
report on the noxious and other insects of the State of New York, 
p. 715-716. 1858. 

Harris, Thaddeus William. A treatise on some of the insects of New 
England which are injurious to vegetation, p. 1-459. (Reference on 
p. 92-93.) 1842. 

Hopkins, A. D. Report on investigations to determine the cause of 
unhealthy conditions of the spruce and pine from 1880-1893. West 
Virginia Agr. Exp.Sta. Bui. 50:195-401. (Reference on p. 439.) 1899. 

Kellogg, Vernon L. Coleoptera. In The development and homologies 
of the mouth parts of insects. Am. nat. 36:090-091. 1902. 

American insects, p. 1-074. (Reference on p. 200.) 1905.. 

KiRBY, William. Hargium lineatum. In Fauna Boreali-Americana 4 : 178. 
1837. 

LeConte, John L. Rhagium. In An attempt to classify the longicorn 
Coleoptera of the part of America north of Mexico. Acad. Nat. Sci. 
Philadelphia. Journ. ser. 2:1:319. 1850. 

Leng, Charles W. Synopses of Cerambycidae. Ent. Amer. 6:65-09. 
1890. 

Olivier, A. G. Stcnoconis lineatus. In Entomologic, ou Histoire 
naturelle des insectes. Coleopteres 4, no. 09. Stencore. Especes no. 
6:13-14. 1795. 

Packard, Alpheus S. The ribbed rhagium. In Descriptions of larvae 
of injurious forest insects. U. S. Ent. Comm. Rept. 3:259-200. 1883. 

The ribbed rhagium. In Insects injurious to forest and 

shade trees. U. S. Ent. Comm. Rept. 5:704-700. 1890. 

A text-book of entomology, p. 1-729. (Reference on p. 67.) 



1898. 



Rathvon, S. S. Entomology and its relations to the vegetable productions 
of the soil, with reference to both destructive and beneficial insects. 
U. S. Comm. Patents. Rept. 1861 : 585-020. 1802. 



Memoir 30, Phosphonxs in Butter, the third preceding number in this series of publications, was mailed 
on June 14, 1920. 









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